Tetrahydrophthalimides, and their production and use as herbicides

ABSTRACT

A compound of the formula: ##STR1## wherein X is a chlorine atom or a bromine atom and R is a C 3  -C 4  alkenyl group or a C 3  -C 4  alkynyl group, which is useful as a herbicide.

The present invention relates to N-(2-fluoro-4-halo-5-substitutedphenyl)-3,4,5,6-tetrahydrophthalimide derivatives (hereinafter referredto as "tetrahydrophthalimide(s)"), and their production and use.

The tetrahydrophthalimides are representable by the formula: ##STR2##wherein X is a chlorine atom or a bromine atom and R is a C₃ -C₄ alkenylgroup (e.g. allyl) or a C₃ -C₄ alkynyl group (e.g. 2-propynyl).

It is known that certain kinds of N-phenyltetrahydrophthalimides areeffective as herbicides. For instance, the herbicidal use of2-fluoro-4-chlorophenyltetrahydrophthalimide,2,4-dichloro-5-isopropoxyphenyltetrahydrophthalimide, etc. is disclosedin U.S. Pat. No. 4,032,326, U.K. Patent Publication No. 2046754A, etc.However, their herbicidal effect is still not always satisfactory.

It has now been found that the tetrahydrophthalimides of formula (I)show a strong herbicidal activity against a wide variety of weedsincluding Gramineae weeds, Cyperaceae weeds and broad-leaved weeds atsmall doses and do not produce any material phytotoxicity on variousagricultural crops. Examples of Gramineae weeds against which thetetrahydrophthalimides (I) show a herbicidal activity are barnyardgrass(Echinochloa crus-galli), green foxtail (Setaria viridis), largecrabgrass (Digitaria sanguinalis), Johnsongrass (Sorghum halepense),wild oat (Avena fatua), water foxtail (Alopecurus geniculatus),goosegrass (Eleusine indica), annual bluegrass (Poa annua), bermudagrass(Cynodon dactylon), quackgrass (Agropyron repens), etc. Examples ofCyperaceae weeds are nutsedge sp. (Cyperus sp.), purple nutsedge(Cyperus rotundus), hardstem bulrush (Scirpus juncoides), nutsedge(Cyperus serotinus), water chestnut (Eleocharis kuroguwai), slenderspikerush (Eleocharis acicularis), etc. Examples of broad-leaved weedsare tall morningglory (Ipomoea purpurea), velvetleaf (Abutilontheophrasti), sicklepod (Cassia obtusifolia), wild sunflower (Helianthusannus), cocklebur (Xanthium pennsylvanicum), wild mustard (Brassicakaber), common chickweed (Stellaria media), common purslane (Portulacaoleracea), jimsonweed (Datura stramonium), hemp sesbania (Sesbaniaexaltata), sun spurge (Euphorbia helioscopia), prickly sida (Sidaspinosa), common ragweed (Ambrosia artemisifolia), smartweed sp.(Polygonum sp.), redroot pigweed (Amaranthus retroflexus), bedstraw(Galium aparine ), pineappleweed (Matricaria spp.), birdseye speedwell(Veronica persica), wild buckwheat (Polygonum convolvulus), ladysthumb(Polygonum persicaria), beggarticks (Bidens spp.), common lambsquarters(Chenopodium album), black nightshade (Solanum nigrum), bindweed(Calystegia japonica), monochoria (Monochoria vaginalis), Americanwaterwort (Elatine americana), false pimpernel (Lindernia procumbens),toothcup (Rotala indica), arrowhead (Sagittaria pygmaea), etc.

Accordingly, the tetrahydrophthalimides (I) can be used as herbicidesapplicable for field crops and vegetables as well as paddy rice. Theyare also useful as herbicides to be employed for orchard, lawn, pasture,tea garden, mulberry field, rubber plantation, forest, etc.applications.

The tetrahydrophthalimides (I) can be produced by various procedures,among which typical examples are shown below.

Procedure A

The tetrahydrophthalimide (I) is obtainable by reacting an aniline ofthe formula: ##STR3## wherein X and R are each as defined above with3,4,5,6-tetrahydrophthalic anhydride, in the absence or presence of aninert solvent (e.g. benzene, toluene, xylene, 1,4-dioxane, acetic acid,propionic acid) while heating. The reaction is normally accomplished ata temperature of 70° to 200° C. for a period of 0.5 to 5 hours. Themolar ratio of the aniline (II) and the tetrahydrophthalic anhydride ispreferred to be from 1:1.0 to 1:1.1.

Procedure B

The tetrahydrophthalimide (I) is obtainable by reacting ahydroxyphenyltetrahydrophthalimide of the formula: ##STR4## wherein X isas defined above with a halide of the formula: RY wherein Y is achlorine atom, a bromine atom or an iodine atom and R is as definedabove, usually in an inert solvent (e.g. dimethylformamide,dimethylsulfoxide) in the presence of a base such as an alkali metalcarbonate (e.g. potassium carbonate), an alkali metal hydroxide (e.g.potassium hydroxide), an alkali metal hydride (e.g. sodium hydride) oran alkali metal alkoxide (e.g. sodium methoxide, sodium ethoxide). Themost preferred base is an alkali metal carbonate. The reactiontemperature is normally from 0° to 100° C., preferably from 40° to 90°C. The molar ratio of the hydroxyphenyltetrahydrophthalimide (III) andthe halide is preferred to be from 1:1.0 to 1:1.1.

The thus produced tetrahydrophthalimide (I) may be, when desired,purified by a per se conventional procedure such as recrystallization orcolumn chromatography.

The aniline (II) as the starting material in Procedure A and thehydroxyphenyltetrahydrophthalimide (III) as the starting material inProcedure B can be produced from a phenol of the formula: ##STR5##wherein X is as defined above according to the following scheme:##STR6## wherein X and R are each as defined above.

Specifically, the aniline (II) may be produced from the phenol (IV) bynitrating the same, subjecting the resultant nitrophenol (V) toalkenylation or alkynylation and reducing the resulting alkenyloxy- oralkynyloxy-nitrobenzene (VI). The hydroxyphenyltetrahydrophthalimide(III) can be manufactured from the phenol (IV) by nitrating the same,reducing the resultant nitrophenol (V) and reacting the resultingaminophenol (VII) with 3,4,5,6-tetrahydrophthalic anhydride.

Conversion of the phenol (IV) into the nitrophenol (V) may beaccomplished by application of a per se conventional nitration procedureto the former. Usually, however, the indirect nitration which consistsof the following three steps is favorable for achieving the selectivenitration at the desired position: ##STR7## wherein X is as definedabove. Thus, the phenol (IV) is converted into its alkali metal salt bytreatment with an aqueous solution of an alkali metal hydroxide (e.g.sodium hydroxide, potassium hydroxide), and the resulting salt isreacted with an alkyl haloformate such as methyl chloroformate in waterat a temperature of 0° to 10° C. The thus prepared carbonic ester (VIII)is nitrated with a mixture of conc. sulfuric acid and conc. nitric acidat room temperature. Then, the nitrobenzene (IX) thus obtained ishydrolyzed with an aqueous alkaline solution such as an aqueous sodiumhydroxide solution at a temperature of 20° to 120° C. to give thenitrophenol (V).

The alkenylation or alkynylation for conversion of the nitrophenol (V)into the alkenyloxy- or alkynyloxynitrobenzene (VI) may be carried outby treatment of the former with an alkali metal carbonate (e.g.potassium carbonate), an alkali metal hydride (e.g. sodium hydride) oran alkali metal alkoxide (e.g. sodium methoxide) and reacting theresultant alkali metal salt with a halide of the formula: RY wherein Rand Y are each as defined above in a polar solvent (e.g. water,dimethylformamide, acetonitrile, acetone, dimethylsulfoxide), usually ata temperature of 10° to 200° C., preferably of 30° to 100° C. The use ofa phase transfer catalyst such as tetrabutylammonium bromide isfavorable for smooth accomplishment of the reaction.

Reduction of the alkenyloxy- or alkynyloxynitrobenzene (VI) to theaniline (II) may be achieved by various procedures. For instance, theremay be adopted reduction with iron powder. Namely, an acetic acidsolution containing one molar amount of the compound (VI) is admixedwith a 5% acetic acid solution containing 2 to 5 molar amount of ironpowder such as reductive iron or electrolytic iron at a temperature of80° to 100° C. and then the reaction is effected at a temperature of 80°to 120° C., preferably of 90° to 110° C., for a period of 0.5 to 5hours.

Conversion of the nitrophenol (V) into the aminophenol (VII) may beaccomplished by any per se conventional reduction procedure for changinga nitro group to an amino group. Examples of such reduction procedureare catalytic reduction, reduction with iron powder, reduction withsodium sulfide, reduction with sulfurated sodium borohydride, etc. Forinstance, treatment of one molar amount of the nitrophenol (V) with a 3molar amount of hydrogen in the presence of a 1/10 to 1/100 molar amountof platinum dioxide in an inert solvent (e.g. ethanol, ethyl acetate) atroom temperature under atmospheric pressure affords the aminophenol(VII). Further, for instance, treatment of one molar amount of thenitrophenol (V) with a 2 to 5 molar amount of iron powder such asreductive iron or electrolytic iron in a 5% acetic acid solution or adilute hydrochloric acid solution at a temperature of 80° to 100° C. fora period of 1 to 5 hours produces the aminophenol (VII).

For production of the hydroxyphenyltetrahydrophthalimide (III) from theaminophenol (VII), the latter is reacted with 3,4,5,6-tetrahydrophthalicanhydride in an inert solvent (e.g. acetic acid) while refluxing for aperiod of 1 to 6 hours, preferably of 2 to 4 hours.

Still, the phenol (IV) is known (cf. Finger et al.: J.Am.Chem.Soc., 81,94 (1959)).

Practical and presently preferred embodiments of the production of theobjective tetrahydrophthalimide (I) as well as the intermediarycompounds including those of the formulas: ##STR8## wherein R' is ahydrogen atom, a C₃ -C₄ alkenyl group or a C₃ -C₄ alkynyl group and X isas defined above are illustratively shown below:

EXAMPLE 1

Production of the tetrahydrophthalimide (I: X=Cl; R=CH.tbd.CCH₂ --):

To a solution ofN-(4-chloro-2-fluoro-5-hydroxyphenyl)-3,4,5,6-tetrahydrophthalimide (1g) in dimethylformamide (10 ml), there was added anhydrous potassiumcarbonate (0.34 g) while stirring at room temperature. After stirringfor 30 minutes at about 40° C., propargyl bromide (1 g) was addedthereto, and the resultant mixture was stirred for 3 hours at 50°-60° C.After being allowed to cool to room temperature, the mixture was pouredinto water and extracted with ether. The ether layer was washed withwater, dried over anhydrous sodium sulfate and concentrated. The residuewas purified by silica gel chromatography to obtain 0.8 g ofN-[4-chloro-2-fluoro-5-(2-propynyloxy)phenyl]-3,4,5,6-tetrahydrophthalimide(Compound No. 3). M.P., 136.4° C.

Elementary analysis (%): Calcd.: C, 61.09; H, 4.00; N, 4.20; Found: C,61.18; H, 4.19; N, 3.92.

NMR (CDCl₃) δ(ppm): 1.8 (4H, m), 2.4 (4H, m), 2.55 (1H), 4.7 (1H), 6.95(1H, d, J=6 Hz), 7.25 (1H, d, J=10 Hz).

IR ν^(nujol) (cm⁻¹): 3260, 1700.

EXAMPLE 2

Production of the tetrahydrophthalimide (I: X=Cl; R=2-propynyl):

4-Chloro-2-fluoro-5-(2-propynyloxy)aniline (1.9 g) and3,4,5,6-tetrahydrophthalic anhydride (1.52 g) were dissolved in aceticacid (20 ml) and refluxed for 3 hours. The resultant mixture was allowedto cool to room temperature and poured into water, followed byextraction with ether. The extract was washed with water, dried overanhydrous sodium sulfate and subjected to filtration. The filtrate wasconcentrated under reduced pressure and the residue was purified bysilica gel chromatography to obtain 1.3 g ofN-[4-chloro-2-fluoro-5-(2-propynyloxy)phenyl]3,4,5,6-tetrahydrophthalimide(Compound No. 3). M.P. 136.4° C.

Examples of the tetrahydrophthalimide (I) produced in the same manner asabove are shown in Table 1.

                  TABLE 1                                                         ______________________________________                                         ##STR9##                                                                       Com-                                                                        pound                                                                         No.                                                                             X          R     Physical property                                          ______________________________________                                        1        Cl    CH.sub.2CHCH.sub.2                                                                           M.P. 56-57° C.                             2      Cl                                                                                   ##STR10##     n.sub.D.sup.25.5 1.5512                           3      Cl    CHCCH.sub.2    M.P. 136.4° C.                             4      Cl                                                                                   ##STR11##     M.P. 115-116° C.                            5     Br    CHCCH.sub.2    M.P. 127-128° C.                           6      Br    CH.sub.2CHCH.sub.2                                                                           M.P. 69-70° C.                           ______________________________________                                    

EXAMPLE 3

Production of the aniline (II: X=Cl; R=CH.tbd.CCH₂ --):

A suspension of electrolytic iron powder (3.5 g) in a 5% aqueous aceticacid solution was heated to 90° C., and a solution of4-chloro-2-fluoro-5-(2-propynyloxy)nitrobenzene (5.7 g) in acetic acid(40 ml) was dropwise added thereto at the same temperature. Theresultant mixture was stirred at 90°-105° C. for 1 hour and allowed tocool to room temperature. Water (200 ml) was added thereto. Insolublematerials were filtered, and the filtrate was neutralized, followed byextraction with ethyl acetate. The extract was dried over anhydrousmagnesium sulfate and concentrated. The residue was washed withpetroleum ether and carbon tetrachloride to obtain 3.6 g of4-chloro-2-fluoro-5-(2-propynyloxy)aniline. M.P. 61.0°-61.5° C.

NMR (CDCl₃) δ(ppm): 2.5 (1H, t, J=2 Hz), 3.4-4.2 (2H, m, J=16 Hz), 4.15(2H, d, J=2 Hz), 6.5 (1H, d, J=8 Hz), 6.95 (1H, d, J=10 Hz).

IR ν_(max) (cm⁻¹): 3460, 3360, 3280, 2100.

Some examples of the anilines (II) produced in the same manner as aboveare shown in Table 2.

                  TABLE 2                                                         ______________________________________                                         ##STR12##                                                                         X     R                 Physical property                                ______________________________________                                        Cl     CH.sub.2CHCH.sub.2                                                                              n.sub.D.sup.19.0 1.5598                              Cl     CHCCH.sub.2       M.P. 61.0-61.5° C.                              Cl                                                                                  ##STR13##        M.P. 67.0-68.0° C.                            ______________________________________                                    

EXAMPLE 4

Production of the hydroxyphenyltetrahydrophthalimide (III: X=Cl):

2-Chloro-4-fluoro-5-aminophenol (6.6 g) and 3,4,5,6-tetrahydrophthalicanhydride (6 g) were dissolved in acetic acid (20 ml) and refluxed for 2hours. The resultant mixture was allowed to cool to room temperature andpoured into ice-water, followed by extraction with ether. The etherextract was washed with a saturated sodium hydrogen carbonate solutionand water in this order, dried over anhydrous magnesium sulfate andconcentrated. The residue was purified by silica gel chromatography toobtain 4.0 g ofN-(4-chloro-2-fluoro-5-hydroxyphenyl)-3,4,5,6-tetrahydrophthalimide.M.P., 151° C.

NMR (CDCl₃, D₆ -DMSO) δ(ppm): 1.5-2.0 (4H, m), 2.1-2.6 (4H, m), 6.8 (1H,d, J=6 Hz), 7.15 (1H, d, J=10 Hz).

IR ν_(max) ^(nujol) (cm⁻¹): 3380, 1680.

EXAMPLE 5

Production of the hydroxyphenyltetrahydrophthalimide (III: X=Br):

In the same manner as in Example 4 but using2-bromo-4-fluoro-5-aminophenol in place of2-chloro-4-fluoro-5-aminophenol, there was producedN-(4-bromo-2-fluoro-5-hydroxyphenyl)-3,4,5,6-tetrahydrophthalimide.M.P., 167°-168° C.

NMR (CDCl₃, D₆ -DMSO) δ(ppm): 1.5-2.0 (4H, m), 2.1-2.7 (4H, m), 6.8 (1H,d, J=6 Hz), 7.25 (1H, d, J=10 Hz).

IR ν_(max) ^(nujol) (cm⁻¹): 3380, 1690.

EXAMPLE 6

Production of the alkynyloxy-nitrobenzene (VI: X=Cl; R=CH.tbd.CCH₂ --):

To a solution of 2-chloro-4-fluoro-5-nitrophenol (19.1 g) inacetonitrile (100 ml), there was added anhydrous potassium carbonate (8g). After stirring at room temperature for several minutes, propargylbromide (14 g) was added thereto, and the resultant mixture was heatedunder reflux for 3 hours. After being allowed to cool to roomtemperature, water was added thereto, and the reaction mixture wasextracted with ether. The ether extract was washed with a 5% aqueoussodium hydroxide solution and water in this order, dried over anhydrousmagnesium sulfate and subjected to filtration. The filtrate wasconcentrated under reduced pressure, and the residue was recrystallizedfrom ethanol to obtain 13.5 g of4-chloro-2-fluoro-5-(2-propynyloxy)nitrobenzene. M.P., 88°-89° C.

NMR (CDCl₃) δ(ppm): 2.55 (1H, t, J=3 Hz), 4.78 (2H, d, J=3 Hz), 7.35(1H, d, J=10 Hz), 7.8 (1H, d, J=6 Hz).

Some of the alkenyloxy- or alkynyloxy-nitrobenzene (VI) compoundsproduced in the same manner as above are shown in Table 3.

                  TABLE 3                                                         ______________________________________                                         ##STR14##                                                                         X     R                 Physical property                                ______________________________________                                        Cl     CH.sub.2 CHCH.sub.2                                                                             n.sub.D.sup.17.0 1.5601                                Cl                                                                                  ##STR15##        M.P. 41.0-41.5° C.                              Cl   CH.sub.2 CCH      M.P. 88-89° C.                                  Cl                                                                                  ##STR16##        M.P. 87-88° C.                                ______________________________________                                    

EXAMPLE 7

Production of the aminophenol (VII: X=Cl):

A suspension of 2-chloro-4-fluoro-5-nitrophenol (9.17 g) and platinumdioxide (500 mg) in ethanol (120 ml) was subjected to catalyticreduction with hydrogen under room temperature and atmospheric pressureuntil a designed amount of hydrogen was absorbed. The catalyst wasremoved by filtration, and the filtrate was concentrated. The residuewas extracted with ether, and the ether layer was concentrated to obtain6.6 g of 3-amino-6-chloro-4-fluorophenol. M.P., 145°-146° C. (decomp.).

NMR (CDCl₃, D₆ -DMSO) δ(ppm): 6.4 (1H, d, J=8 Hz), 6.85 (1H, d, J=11Hz).

IR ν_(max) ^(nujol) (cm⁻¹): 3400, 3320.

EXAMPLE 8

Production of the aminophenol (VII: X=Br):

In the same manner as above but using 2-bromo-4-fluoro-5-nitrophenol inplace of 2-chloro-4-fluoro-5-nitrophenol, there was produced3-amino-6-bromo-4-fluorophenol. M.P., 129°-130.5° C. (decomp.).

NMR (CDCl₃, D₆ -DMSO) δ(ppm): 6.57 (1H, d, J=8 Hz), 7.1 (1H, d, J=11Hz).

IR ν_(max) ^(nujol) (cm⁻¹): 3400, 3320.

EXAMPLE 9

Production of the nitrophenol (V: X=Cl):

2-Chloro-4-fluorophenol (83.4 g) was added to a solution of sodiumhydroxide (27.7 g) in water (450 ml), and methyl chloroformate (69.2 g)was dropwise added thereto at a temperature of below 10° C. Precipitatedcrystals were collected by filtration and washed with water to givemethyl (2-chloro-4-fluorophenyl)formate (134.8 g). M.P., 69°-71° C.

Methyl (2-chloro-4-fluorophenyl)formate (134.8 g) obtained above wassuspended in conc. sulfuric acid (50 ml). To the suspension, a mixtureof conc. sulfuric acid (50 ml) and conc. nitric acid (50 ml) was addedat about 30° C., and the mixture was stirred for 1 hour at thistemperature. The reaction mixture was poured into ice water, andprecipitated crystals were collected and washed with water. Methyl(2-chloro-4-fluoro-5-nitrophenyl)formate (143 g) was thus obtained.M.P., 53°-55° C.

The product obtained as above was combined with sodium hydroxide (27 g)and water (300 ml), and the resultant mixture was refluxed for 4 hours.Precipitated insoluble materials were filtered using a celite, and thefiltrate was acidified with conc. hydrochloric acid. Precipitatedcrystals were filtered and washed with water to obtain 76.3 g of2-chloro-4-fluoro-5-nitrophenol. M.P. 106°-107° C.

NMR (CDCl₃, D₆ -DMSO) δ(ppm): 7.25 (1H, d, J=10 Hz), 7.64 (1H, d, J=6Hz).

IR ν_(max) ^(nujol) (cm⁻¹): 3370.

EXAMPLE 10

Production of the nitrophenol (V: X=Br):

2-Bromo-4-fluorophenol (28 g) was added to a solution of sodiumhydroxide (7 g) in water (100 ml), and methyl chloroformate was dropwiseadded thereto at a temperature of below 10° C. Precipitated crystalswere collected by filtration and washed with water to give methyl(2-bromo-4-fluorophenyl)formate (41 g). M.P., 80.7° C.

The thus obtained methyl (2-bromo-4-fluorophenyl)formate was suspendedin conc. sulfuric acid (13 ml). To the suspension, a mixture of conc.sulfuric acid (13 ml) and conc. nitric acid (13 ml) was added at about30° C. The mixture was stirred for 30 minutes and poured onto ice.Precipitated crystals were thoroughly washed with water, whereby yellowcrystals of methyl (2-bromo-4-fluoro-5-nitrophenyl)formate (38.3 g) wereobtained. M.P., 63.5°-64.5° C.

The product thus obtained was refluxed together with sodium hydroxide(6.2 g) and water (100 ml) for 3 hours. Insoluble materials werefiltered, and the filtrate was acidified with hydrochloric acid.Precipitated crystals were collected by filtration and washed with waterto obtain 25 g of 2-bromo-4-fluoro-5-nitrophenol. M.P., 126°-127° C.

NMR (CDCl₃, D₆ -DMSO) δ(ppm): 7.42 (1H, d, J=10 Hz), 7.65 (1H, d, J=6Hz).

IR ν_(max) ^(nujol) (cm⁻¹): 3450.

In the practical usage of the tetrahydrophthalimides (I), they may beapplied as such or in any preparation form such as wettable powders,emulsifiable concentrates, granules, suspensions or dusts.

In producing such a preparation form, a solid or liquid carrier may beused. As for the solid carrier, there may be exemplified mineral powders(e.g. kaolin, bentonite, montmorillonite, talc, diatomaceous earth,mica, vermiculite, gypsum, calcium carbonate, apatite, syntheticwater-containing silicon hydroxide), vegetable powders (e.g. soybeanpowder, wheat flour, wooden powder, tabacco powder, starch, crystallinecellulose), high molecular weight compounds (e.g. petroleum resin,polyvinyl chloride, dammar gum, ketone resin), alumina, wax and thelike.

As for the liquid carrier, ther may be exemplified alcohols (e.g.methanol, ethanol, ethylene glycol, benzyl alcohol), aromatichydrocarbons (e.g. toluene, benzene, xylene, methylnaphthalene),halogenated hydrocarbons (e.g. chloroform, carbon tetrachloride,monochlorobenzene), ethers (e.g. dioxane, tetrahydrofuran), ketones(e.g. acetone, methylethylketone, cyclohexanone), esters (e.g. ethylacetate, butyl acetate, ethylene glycol acetate), acid amides (e.g.dimethylformamide), nitriles (e.g. acetonitrile), ether alcohols (e.g.ethylene glycol ethyl ether), water and the like.

A surface active agent used for emulsification, dispersion or spreadingmay be any of the non-ionic, anionic, cationic and amphoteric type ofagents. Examples of the surface active agent include polyoxyethylenealkyl ethers, polyoxyethylene alkylaryl ethers, polyoxyethylene fattyacid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fattyacid esters, oxyethyleneoxypropylene polymers, polyoxyethylene alkylphosphates, fatty acid salts, alkyl sulfates, alkyl sulfonates,alkylaryl sulfonates, alkyl phosphates, polyoxyethylene alkyl sulfate,quaternary ammonium salts, and the like. But the surface active agent isnot of course limited to these compounds. And, if necessary, gelatin,casein, sodium alginate, starch, agar, polyvinyl alcohol, ligninsulfonicacid or the like may be used as an auxiliary agent.

In the preparation of a herbicidal composition, the content of thetetrahydrophthalimide (I) may be from 1 to 95% by weight, preferablyfrom 3 to 80% by weight.

The tetrahydrophthalimide (I) of the invention may be used together withother herbicides to improve their activity as herbicides, and in somecases, a synergistic effect can be expected. Further, they may be alsoapplied in combination with insecticides, nematocides, fungicides, plantgrowth regulators or fertilizers, depending upon needs.

The dosage rate of the tetrahydrophthalimide (I) may vary depending ontheir kinds, the sorts of cultivated plants, the modes of application,etc. Generally, however, the dosage rate is from 0.1 to 50 grams,preferably from 0.5 to 30 grams, of the active ingredient per are.

Practical embodiments of the herbicidal composition according to theinvention are illustratively shown in the following examples whereinparts and % are by weight.

PREPARATION EXAMPLE 1

Eighty parts of Compound No. 1, 2 or 3, 3 parts of alkylsulfate, 2 partsof ligninsulfonate and 15 parts of water-containing silicon hydroxideare well mixed while being powdered to obtain a wettable powder.

PREPARATION EXAMPLE 2

Ten parts of Compound No. 1, 2 or 5, 3 parts of alkylarylsulfate, 7parts of polyoxyethylene alkylaryl ether, 60 parts of cyclohexanone and20 parts of xylene are well mixed while being powdered to obtain anemulsifiable concentrate.

PREPARATION EXAMPLE 3

Five parts of Compound No. 1 or 2, 1 part of water-containing siliconhydroxide, 35 parts of bentonite and 59 parts of kaolin are well mixedwhile being powdered. The mixture is then kneaded with water, granulatedand dried to obtain a granule.

PREPARATION EXAMPLE 4

Three parts of Compound No. 1, 2 or 3, 0.3 part of isopropyl phosphate,66.7 parts of kaolin and 30 parts of talc are well mixed while beingpowdered to obtain a dust.

PREPARATION EXAMPLE 5

Twenty parts of Compound No. 6 is mixed with 60 parts of an aqueoussolution containing 3% polyoxyethylene sorbitan monolaurate and graineduntil the particle size of the active ingredient becomes less than 3microns. Twenty parts of an aqueous solution containing 3% of sodiumalginate as a dispersing agent is introduced therein to obtain asuspension.

The application of the tetrahydrophthalimides (I) as herbicides will beillustratively shown in the following Examples wherein the phytotoxicityto cultivated plants and the herbicidal activity on weeds were evaluatedas follows: the aerial parts of the test plants were cut off and weighed(fresh weight); the percentage of the fresh weight of the treated plantto that of the untreated plant was calculated with the latter freshweight taken as 100; and the crop damage and the herbicidal activitywere evaluated by the standard given in the table below. The ratingvalues of phytotoxicity, 0 and 1, and those of herbicidal effect, 5 and4, are generally regarded as satisfactory to protect cultivated plantsand control weeds, respectively. The rating values in the paddy fieldtest alone were calculated from the dry weight of the test plants.

    ______________________________________                                                   Fresh weight                                                       Rating     (percentage to untreated plot) (%)                                 value      Crop plant  Weeds                                                  ______________________________________                                        5           0-39       0                                                      4          40-59        1-10                                                  3          60-79       11-20                                                  2          80-89       21-40                                                  1          90-99       41-60                                                  0          100          61-100                                                ______________________________________                                    

The following control compounds were used in the Examples:

    ______________________________________                                        Compound                                                                      No.     Structure            Remarks                                          ______________________________________                                                 ##STR17##           U.S. Pat. No. 4,032,326                            B                                                                                    ##STR18##           U.K. Patent Publn. No. 2046754A                    C                                                                                    ##STR19##           Atrazine                                         ______________________________________                                    

TEST EXAMPLE 1

Plastic trays (35 cm×25 cm×10 cm) were filled with upland field soil,and the seeds of corn, velvetleaf, sunflower, sicklepod, tallmorningglory, wild mustard and common chickweed were separately sowed inthe trays and grown for 2 weeks in the greenhouse. Each of two trays wasset in a frame (50 cm×100 cm×40 cm) and a designed amount of the testcompound was sprayed to the foliage of the test plants over the top bymeans of a small hand sprayer. After the spraying, the test plants werefurther grown for 3 weeks in the greenhouse, and herbicidal activity andphytotoxicity were examined. The results are shown in Table 4. In thisfoliar treatment, the test compounds were formulated into anemulsifiable concentrate according to Preparation Example 2 and appliedby dispersing it in 25 ml of water with the addition of a spreadingagent. At the time of application, the test plants were in a 1 to 3-leafstage and 2 to 20 cm in height.

                                      TABLE 4                                     __________________________________________________________________________    Dosage                                                                        (weight of                                                                    active in-  Phyto-                                                                            Herbicidal activity                                           Compound                                                                            gredient,                                                                           toxicity                                                                          Velvet-                                                                            Sun-                                                                              Sickle-                                                                           Tall morning-                                                                        Wild Common                               No.   g/are)                                                                              Corn                                                                              leaf flower                                                                            pod glory  mustard                                                                            chickweed                            __________________________________________________________________________    3     1.25  1   5    5   5   5      5    5                                          0.63  0   5    5   4   5      5    4                                          0.32  0   5    5   4   5      3    3                                    5     1.25  1   5    5   5   5      5    5                                          0.63  1   5    5   4   5      5    4                                          0.32  0   5    4   3   5      5    3                                    A     10    3   5    5   4   5      5    2                                          5     3   5    5   4   5      4    1                                          2.5   2   5    4   3   4      3    1                                          1.25  1   3    2   1   3      2    0                                    B     10    3   5    5   4   5      5    3                                          5     2   5    5   3   4      4    2                                          2.5   2   4    4   2   4      3    1                                          1.25  0   2    3   0   2      1    0                                    C     10    0   5    5   2   5      5    5                                          5     0   3    5   0   4      5    5                                    __________________________________________________________________________

TEST EXAMPLE 2

Plastic beakers (diameter, 10 cm; height, 10 cm) were filled with uplandfield soil, and the seeds of corn, barnyardgrass, wild oat, wild mustardand velvetleaf were separately sowed in the beakers and grown for 2weeks in the greenhouse. A designed amount of the test compound wassprayed to the foliage of the test plants by means of a small handsprayer. After the spraying, the test plants were further grown for 3weeks in the greenhouse, and herbicidal activity was examined. Theresults are shown in Table 5. In this foliar treatment, the testcompounds were formulated into an emulsifiable concentrate according toPreparation Example 2 and applied at a spray volume of 5 liters per areby dispersing it in water with the addition of a spreading agent.

                  TABLE 5                                                         ______________________________________                                        Dosage                                                                        (weight of           Herbicidal activity                                      Com-   active in-                                                                              Phyto-  Barn-                                                pound  gredient, toxicity                                                                              yard  Wild Wild  Velvet-                             No.    g/are)    Corn    grass oat  mustard                                                                             leaf                                ______________________________________                                        1      5         1       5     5    5     5                                          1.25      1       4     4    5     5                                   2      5         1       5     5    5     5                                          1.25      0       5     4    5     5                                   3      5         1       5     5    5     5                                          1.25      1       5     5    5     5                                   4      5         1       5     5    5     5                                          1.25      1       5     5    5     5                                   5      5         1       5     5    5     5                                          1.25      0       3     4    5     5                                   6      5         1       5     5    5     5                                          1.25      1       4     5    5     5                                   A      5         2       3     1    5     5                                          1.25      1       1     0    3     5                                   B      5         1       2     1    3     5                                          1.25      0       0     0    2     5                                   ______________________________________                                    

TEST EXAMPLE 3

Seeds of corn and broad-leaved weeds such as cocklebur, common purslaneand tall morningglory were sowed in the field as previously laid up inridges, each ridge having an upper width of 1 m. At the time when thecorn grew up to the 6-leaf stage and the broad-leaved weeds up to 2 to5-leaf stages, a designed amount of the test compound formulated into anemulsifiable concentrate according to Preparation Example 2 anddispersed in water was sprayed to the foliage of the test plants withthree replications over the top by means of a small hand sprayer at aspray volume of 5 liters per are. After cultivation for 3 weeks,herbicidal activity and phytotoxicity were examined. The results areshown in Table 6.

                  TABLE 6                                                         ______________________________________                                               Dosage                                                                        (weight of                                                             Com-   active in-                                                                              Phyto-  Herbicidal activity                                  pound  gredient, toxicity                                                                              Cock- Common Tall morning-                           No.    g/are)    Corn    lebur purslane                                                                             glory                                   ______________________________________                                        3      0.63      2       5     5      5                                              0.32      1       5     5      4                                              0.16      1       5     5      4                                       A      1.25      1       4     3      2                                              0.63      0       1     2      2                                       B      1.25      1       4     4      4                                              0.63      1       2     3      3                                       ______________________________________                                    

TEST EXAMPLE 4

Plastic trays (35 cm×25 cm×15 cm) were filled with upland field soil,and the seeds of tall morningglory, velvetleaf and sicklepod and theseeds of corn were sowed therein. A designed amount of the testcompounds formulated into a wettable powder according to PreparationExample 1 was dispersed in water and applied by spraying at a sprayvolume of 5 liters per are to the whole surface of the soil. After thespraying, the test plants were placed in a greenhouse and grown for 20days, and herbicidal activity and phytotoxicity were examined. Theresults are shown in Table 7.

                  TABLE 7                                                         ______________________________________                                               Dosage                                                                        (weight of                                                             Com-   active in-                                                                              Phyto-  Herbicidal activity                                  pound  gredient, toxicity                                                                              Tall morning-                                                                          Sickle-                                                                             Velvet-                               No.    g/are)    Corn    glory    pod   leaf                                  ______________________________________                                        1      10        0       5        4     5                                            5         0       4        4     5                                     2      10        1       5        4     5                                            5         0       4        4     5                                     4      10        0       5        4     5                                            5         0       4        4     5                                     A      10        3       0        1     4                                            5         2       0        0     3                                     B      10        0       0        1     3                                            5         0       0        0     1                                     ______________________________________                                    

TEST EXAMPLE 5

Plastic beakers (diameter, 10 cm; height, 10 cm) were filled with uplandfield soil, and the seeds of corn, cotton and soybean and the seeds ofmorningglory, velvetleaf, Johnsongrass and green foxtail were separatelysowed in the beakers. A designed amount of the test compound was sprayedover the top by means of a small hand sprayer. After the spraying, thetest plants were grown for 20 days in the greenhouse, and herbicidalactivity and phytotoxicity were examined. The results are shown in Table8. In this pre-emergence treatment, the test compounds were formulatedinto an emulsifiable concentrate according to Preparation Example 2 andapplied at a spray volume of 5 liters per are by dispersing it in waterwith the addition of a spreading agent.

                                      TABLE 8                                     __________________________________________________________________________    Dosage                                                                        (weight of                                                                    active in-              Herbicidal activity                                   Compound                                                                            gredient,                                                                           Phytotoxicity                                                                             Morning-                                              No.   g/are)                                                                              Corn                                                                             Cotton                                                                            Soybean                                                                            glory                                                                              Velvetleaf                                                                          Johnsongrass                                                                         Green foxtail                       __________________________________________________________________________    3     10    1  2   --   5    5     5      5                                         2.5   1  0   --   4    5     4      4                                   5     10    1  2   2    5    5     5      5                                         2.5   0  1   0    4    5     4      4                                   6     10    0  --  --   4    5     4      4                                         2.5   0  --  --   --   4     4      4                                   A     10    2  --  --   2    5     3      4                                         2.5   0  --  --   1    4     1      1                                   B     20    1  --  --   1    3     2      0                                         5     0  --  --   0    1     1      0                                   __________________________________________________________________________

TEST EXAMPLE 6

Wagner's pots (1/5000 are) were filled with paddy field soil containingthe seeds of broad-leaved weeds (e.g. monochoria, false pimpernel,toothcup) and the seeds of barnyardgrass and hardstem bulrush, and waterwas poured therein until the depth of water became 4 cm. Rice seedlingsof the 3.5-leaf stage and the tubers of arrowhead were transplantedtherein and grown for 2 days in a greenhouse. A designed amount of thetest compound formulated in an emulsifiable concentrate according toPreparation Example 2 were applied to the pots by perfusion. Thereafter,the test plants were grown for an additional 3 weeks in the greenhouse,and herbicidal activity and phytotoxicity were examined. The results areshown in Table 9. In this treatment, the emulsifiable concentrate wasdispersed in water for application at a perfusion volume of 10 litersper are.

                                      TABLE 9                                     __________________________________________________________________________    Dosage                                                                        (weight of  Phyto-                                                            active in-  toxicity                                                                          Herbicidal activity                                           Compound                                                                            gredient,                                                                           Rice                                                                              Barnyard-                                                                           Broad-leaved                                                                         Hardstem                                                                           Arrow-                                      No.   g/are)                                                                              plant                                                                             grass weed   bulrush                                                                            head                                        __________________________________________________________________________    3     2.5   1   5     5      5    5                                                 1.25  1   5     5      4    4                                           5     2.5   1   5     5      5    5                                                 1.25  1   5     5      4    --                                          A     2.5   1   2     5      3    0                                                 1.25  0   1     5      2    0                                           B     2.5   0   3     5      2    0                                                 1.25  0   1     5      1    0                                           __________________________________________________________________________

What is claimed is:
 1. A compound of the formula: ##STR20## wherein X isa chlorine atom or a bromine atom and R is a C₃ -C₄ alkenyl group, a C₃-C₄ alkynyl group or a hydrogen atom.
 2. The compound according to claim1, wherein X is a chlorine atom and R is a 2-propenyl group.
 3. Thecompound according to claim 1, wherein X is a bromine atom and R is a2-propenyl group.
 4. The compound according to claim 1, wherein X is achlorine atom and R is a 2-propynyl group.
 5. The compound according toclaim 1, wherein X is a bromine atom and R is a 2-propynyl group.
 6. Aherbicidal composition which comprises the compound according to claim 1as an active ingredient and an inert carrier.
 7. A method forcontrolling weeds which comprises applying as an active ingredient aherbicidally effective amount of the compound of the formula: ##STR21##wherein X is a chlorine atom or a bromine atom and R is a C₃ -C₄ alkenylgroup or a C₃ -C₄ alkynyl group.
 8. A compound of the formula: ##STR22##wherein X is a chlorine atom or a bromine atom.